docs: def lines(self, lines):
          """
          Fill Dockerfile content with specified lines
          :param lines: list of lines to be written to Dockerfile
          """
          if self.cache_content:
              self.cached_content = ''.join([b2u(l) for l in lines])
  
          try:
              with self._open_dockerfile('wb') as dockerfile:
                  dockerfile.writelines([u2b(l) for l in lines])
          except (IOError, OSError) as ex:
              logger.error("Couldn't write lines to dockerfile: %r", ex)
              raise